New York and London Fashion Weeks have just come to a close, and here's the skinny on this season's hottest trend. This autumn's must-have accessory? Curves.

They're two of the most agenda-setting events on the fashion calendar. But after years of skin-and-bones models and unforgiving designs, last week the Mad Men effect finally rippled on to the runway too.

Big beauties Lizzie Miller and Toccara Jones left their stick-thin counterparts in the shade at the first ever plus-size fashion show at NYFW. Meanwhile across the pond at LFW, size 12 Kelly Brook and pregnant Abbey Clancy were modelling for designer Giles Deacon.

Showcasing fashion from size 16 upwards, the OneStopPlus.com celebration of curves at the Lincoln Centre last Wednesday marked a milestone for women ostracised by scrawny style.

And it proved that the women of substance usually condescended to by the catty world of haute couture are "equally as beautiful and fashionable", says Zahir Babvani of the brand.

"[The show was] a collaborative effort to provide the extraordinary community of plus-size women with the uncompromising style that they have always deserved but never received," said the vice-president of design of the US company.

The plus-size spectacular is indicative of fashion's new curve towards putting bigger girls on the runway.

Earlier this year, top designers such as Marc Jacobs and Prada included fuller-figured lovelies in their shows for autumn. Meanwhile, Italy became the first country in the world to ban size-zero models from the catwalks.

So if the heroin chic aesthetic embodied by Kate Moss is finally wearing thin, who is to be the new anti-waif?

Step up Lizzie Miller.

The 21-year-old Californian blonde shot to fame when she posed in little more than a smile for Glamour magazine last August, showing off -- wait for it -- a miniscule spare tyre and stretch marks.

Run alongside an article about body image, the photo went viral; and within days, the WeightWatchers graduate had become the unwitting poster girl for America's plus-size movement.

Toppling the prevailing fashion order on its head, now the 5ft 11in, size-12 pin-up is one of the most in-demand clothes hangers in New York.

"I am now really busy," says Miller. "I am working for clients that were once kind of on-the-fence about me. But now they want me.

"I don't think this will be like every other time when something happened and it was just a flash in the pan. I felt that it will be different." Bullied at school, Miller's 'fat' is now her fortune.

"I was known as the funny, fat girl," she adds. "It was horrible. Now I just laugh. My hips and thighs are how I make my living."

Elsewhere, Crystal Renn also resisted advice to lose a third of her body weight -- only to go on to grace the cover of Harper's Bazaar. While Mad Men's sexpot Christina Hendricks has just been snapped up as the face of fashion label London Fog -- despite bemoaning that she can't get free frocks to fit her frame.

But are cultural mores really reverting back to the days of Marilyn and Sophia, or is it all just a storm in a D-cup?

"To be a plus-size model, you still have to be incredibly toned and stunning -- they're not just 'regular' girls. I guarantee you these girls are in the gym every day and eating healthily." But don't confuse plus-size with Prêt-à-Portly, agrees Brenda O'Sullivan of fashion catalogue Simply Be.

"Let's remember the average Irish woman is a size 16," says Brenda. "The catwalks and magazines have managed to distort the perception of the average female body so that we think anything over size zero is 'plus-size'."

The brand is set to crown the owner of the Ireland's best curves at the upcoming Simply Be Curvy 2011 competition final in Dublin.

Outgoing beauty queen Brianna Connaughton (25) admits she never saw herself as model material. "Winning the competition last year opened a whole new chapter in my life," tells the Garda youth project co-coordinator from Waterford. "I wanted to show that beauty is more than being a size 8."

"I'm doing fashion shows every week and most clients are asking for a fuller girl," reveals Jules Fallon. "At the minute, most of my girls are size 8-10, but if it continues, I will consider adding more plus-size girls to my books."

So will it continue, or will snooty designers dictate that plus-size is so last season?

British designer Julien MacDonald has slated the notion of a curvy girl winning Britain's Next Top Model: "You can't have a plus-size girl winning -- it makes it a joke."

"I don't think we'll ever see the end of size zero," says Jules. "Right now, the nation is getting larger and the fashion world is cashing in on that.

"I think designers will inevitably go back to using tiny sample sizes on the catwalk. For now, anything that shows regular girls that big can be beautiful is a good thing."